1. Field of Invention
The present invention relates to the area of fire resistant yarns and products made therefrom, particularly in the area of fire resistant sewing threads.
2. Discussion of the Background
A demand has developed for sewing thread that is heat and fire resistant. Such thread is used in sewing together the cover fabric for pillows, mattresses, bedding, and quilts for institutional use, as well as for sewing together the fabric used in safety apparel.
Sewing thread, because of the nature of its use, must be able to withstand the stresses created thereon by the many repeated bends and jerks occurring during the conventional sewing operation. Therefore it must be able to elongate without breaking.
Conventional sewing threads are made of cotton, nylon, or polyester. Each of these will either burn or melt in the presence of flame or high heat. Such fibers as aramids (KEVLAR®, CONEX®, and NOMEX®) are known to be heat resistant, but they are relatively inelastic and do not elongate. When used alone, threads made from these fibers do not provide as high a level of sewing performance as that provided by threads made from conventional fibers. These and other high performance fibers are also very expensive. Thus the use of such fibers has generally been limited to yarns for knitting and weaving.
Fiberglass is known to have excellent fire resistant capabilities, but problems exist with weaving or knitting it by itself. Therefore it only exists when blended, entangled or twisted with other fibers or filaments.
There still exists a need for a sewing thread that, in addition to functioning as a sewing thread, will withstand the high temperatures (greater than 1,000 degrees centigrade) of a fire. In such a case the sewing thread must maintain its integrity in the presence of high temperatures and flames to keep the seams of mattresses, pillows, and similar products intact, so that more flammable materials inside are not exposed to the flames. In the case of apparel the seams must remain intact to protect the worker.